A Highly Sensitive ELISA D-Dimer Increases Testing but Not Diagnosis of Pulmonary Embolism

Objectives: To determine the effect of introducing a rapid enzyme‐linked immunosorbent assay (ELISA) D‐dimer on the percentage of emergency department (ED) patients evaluated for pulmonary embolism (PE), the use of associated laboratory testing, pulmonary vascular imaging, and the diagnoses of PE. Methods: Patients evaluated for PE during three 120‐day periods were enrolled: immediately before (period 1), immediately after (period 2), and one year after the introduction of a rapid ELISA D‐dimer in the hospital. The frequency of ED patients evaluated for PE with any test, with D‐dimer testing, and with pulmonary vascular imaging and the frequency of PE diagnosis during each time period were determined. Results: The percentage of patients evaluated for PE nearly doubled; from 1.36% (328/24,101) in period 1 to 2.58% (654/25,318) in period 2 and 2.42% (583/24,093) in period 3. The percentage of patients who underwent D‐dimer testing increased more than fourfold; from 0.39% (93/24,101) in period 1 to 1.83% (464/25,318) in period 2 and 1.77% (427/24,093) in period 3. The percentage of patients who underwent pulmonary vascular imaging increased from 1.02% (247/24,101) in period 1 to 1.36% (344/25,318) in period 2 and to 1.39% (334/24,093) in period 3. There was no difference in the percentage of patients diagnosed as having PE in period 1 (0.20% [47/24,101]), period 2 (0.27% [69/25,318]), and period 3 (0.24% [58/24,093]). Conclusions: In the study's academic ED, introduction of ELISA D‐dimer testing was accompanied by an increase in PE evaluations, D‐dimer testing, and pulmonary vascular imaging; there was no observed change in the rate of PE diagnosis.     

Accuracy of Very Low Pretest Probability Estimates for Pulmonary Embolism Using the Method of Attribute Matching Compared with the Wells Score

Objectives: Attribute matching matches an explicit clinical profile of a patient to a reference database to estimate the numeric value for the pretest probability of an acute disease. The authors tested the accuracy of this method for forecasting a very low probability of venous thromboembolism (VTE) in symptomatic emergency department (ED) patients. Methods: The authors performed a secondary analysis of five data sets from 15 hospitals in three countries. All patients had data collected at the time of clinical evaluation for suspected pulmonary embolism (PE). The criterion standard to exclude VTE required no evidence of PE or deep venous thrombosis (DVT) within 45 days of enrollment. To estimate pretest probabilities, a computer program selected, from a large reference database of patients previously evaluated for PE, patients who matched 10 predictor variables recorded for each current test patient. The authors compared the outcome frequency of having VTE [VTE(+)] in patients with a pretest probability estimate of <2.5% by attribute matching, compared with a value of 0 from the Wells score. Results: The five data sets included 10,734 patients, and 747 (7.0%, 95% confidence interval [CI] = 6.5% to 7.5%) were VTE(+) within 45 days. The pretest probability estimate for PE was <2.5% in 2,975 of 10,734 (27.7%) patients, and within this subset, the observed frequency of VTE(+) was 48 of 2,975 (1.6%, 95% CI = 1.2% to 2.1%). The lowest possible Wells score (0) was observed in 3,412 (31.7%) patients, and within this subset, the observed frequency of VTE(+) was 79 of 3,412 (2.3%, 95% CI = 1.8% to 2.9%) patients. Conclusions: Attribute matching categorizes over one‐quarter of patients tested for PE as having a pretest probability of <2.5%, and the observed rate of VTE within 45 days in this subset was <2.5%. ACADEMIC EMERGENCY MEDICINE 2010; 17:133–141 © 2010 by the Society for Academic Emergency Medicine     

The Probability of Pulmonary Embolism Is a Function of the Diagnoses Considered Most Likely Before Testing

Objectives: To determine the frequency of pulmonary embolism (PE) diagnosis when different alternative diagnoses were considered most likely before testing, because the relationship between specific alternative diagnoses and the diagnosis of PE has not been explored.
Methods: This study was a preplanned secondary analysis of a prospective study of the diagnosis of pulmonary embolism conducted in the emergency department (ED) of an urban university hospital. Physicians were queried as to their most likely pretest diagnosis when they ordered any of the following tests to evaluate possible PE: D-dimer, contrast-enhanced computed tomography of the chest, ventilation–perfusion lung scan, or pulmonary angiogram. To compare the frequency of PE diagnosis across alternative diagnoses, risk ratios, 95% confidence intervals (CI), and p-values using Fisher's exact test were calculated.
Results: Six hundred seven patients were enrolled, and 61 had PE. Physicians thought PE was the most likely pretest diagnosis in 162 (26.7%) patients, and 20.4% (95% CI = 14.4% to 27.4%) of these patients had PE. For four alternative diagnoses, PE was diagnosed less frequently than when PE was considered most likely: musculoskeletal pain (2.2%, 95% CI = 0.4% to 6.2%), anxiety (1.7%, 95% CI = 0.0 to 9.2%), asthma or chronic obstructive pulmonary disease (0, 95% CI = 0.0 to 10.9%), and viral syndrome (0, 95% CI = 0.0 to 14.3%).
Conclusions: The frequency of PE is related to the most likely pretest alternative diagnosis. PE is diagnosed infrequently when anxiety, asthma or chronic obstructive pulmonary disease, musculoskeletal pain, or viral syndrome is the most likely alternative diagnosis.     

D-dimer levels during delivery and the postpartum

BACKGROUND: D-dimer (DD) measurement has proved to be very useful to exclude venous thromboembolism (VTE) in outpatients. However, during pregnancy, the progressive increase as well as the interindividual variations of DD means that in this instance they are of poor value to rule out VTE. Only a few studies have reported measurements of DD levels in the postpartum. OBJECTIVES: To measure DD sequentially in the puerperium in order to determine when DD levels return to values obtained in non-pregnant women and can again be used in the exclusion of VTE. PATIENTS AND METHODS: After uncomplicated pregnancies, 150 women delivering at term either vaginally (n = 100) or by cesarean section (n = 50) were included. DD levels were measured immediately following delivery and next at days 1, 3, 10, 30 and 45. RESULTS: There was a marked elevation of DD at delivery, especially when instrumental. All DD measurements were above 500 ng mL(-1) at delivery, at day 1 and at day 3 postpartum. A sharp decrease in DD was observed between day 1 and day 3, followed by a slight increase at day 10. At day 30 and day 45, respectively, 79% and 93% of women in the vaginal delivery group and 70% and 83% in the cesarean group had levels below 500 ng mL(-1). Bleeding, breastfeeding and heparin prophylaxis did not modify DD levels significantly. CONCLUSION: Using the Vidas DD new assay, our study provides reference intervals for DD in the postpartum period. Using a cut-off at 500 ng mL(-1), DD measurement for ruling out VTE was found to be useful again 4 weeks after delivery.     

Diagnostic accuracy of D-dimer test for exclusion of venous thromboembolism: a systematic review

Summary.  Background: The reported diagnostic accuracy of the D-dimer test for exclusion of deep vein thrombosis (DVT) and pulmonary embolism (PE) varies. It is unknown to what extent this is due to differences in study design or patient groups, or to genuine differences between D-dimer assays. Methods: Studies evaluating the diagnostic accuracy of the D-dimer test in the diagnosis of venous thromboembolism were systematically searched for in the MEDLINE and EMBASE databases up to March 2005. Reference lists of all included studies and of reviews related to the topic of the present meta-analysis were manually searched for other additional potentially eligible studies. Two reviewers independently extracted study characteristics using standardized forms. Results: In total, 217 D-dimer test evaluations for DVT and 111 for PE were analyzed. Several study design characteristics were associated with systematic differences in diagnostic accuracy. After adjustment for these features, the sensitivities of the D-dimer enzyme-linked immunofluorescence assay (ELFA) (DVT 96%; PE 97%), microplate enzyme-linked immunosorbent assay (ELISA) (DVT 94%; PE 95%), and latex quantitative assay (DVT 93%; PE 95%) were superior to those of the whole-blood D-dimer assay (DVT 83%; PE 87%), latex semiquantitative assay (DVT 85%; PE 88%) and latex qualitative assay (DVT 69%; PE 75%). The latex qualitative and whole-blood D-dimer assays had the highest specificities (DVT 99%, 71%; PE 99%, 69%). Conclusions: Compared to other D-dimer assays, the ELFA, microplate ELISA and latex quantitative assays have higher sensitivity but lower specificity, resulting in a more confident exclusion of the disease at the expense of more additional imaging testing. These conclusions are based on the most up-to-date and extensive systematic review of the topic area, including 184 articles, with 328 D-dimer test evaluations.     

Value of Quantitative D-dimer Assays in Identifying Pulmonary Embolism: Implications from a Sequential Decision Model

Objectives: To examine the cost-effectiveness of a quantitative D-dimer assay for the evaluation of patients with suspected pulmonary embolism (PE) in an urban emergency department (ED).
Methods: The authors analyzed different diagnostic strategies over pretest risk categories on the basis of Wells criteria by using the performance profile of the ELISA D-dimer assay (over five cutoff values) and imaging strategies used in the ED for PE: compression ultrasound (CUS), ventilation–perfusion (VQ) scan (over three cutoff values), CUS with VQ (over three cutoff values), computed tomography (CT) angiogram (CTA) with pulmonary portion (CTP) and lower-extremity venous portion, and CUS with CTP. Data used in the analysis were based on literature review. Incremental costs and quality-adjusted-life-years were the outcomes measured.
Results: Computed tomography angiogram with pulmonary portion and lower-extremity venous portion without D-dimer was the preferred strategy. CUS-VQ scanning always was dominated by CT-based strategies. When CTA was infeasible, the dominant strategy was D-dimer with CUS-VQ in moderate- and high-Wells patients and was D-dimer with CUS for low-Wells patients. When CTP specificity falls below 80%, or if its overall performance is markedly degraded, preferred strategies include D-dimer testing. Sensitivity analyses suggest that pessimistic assessments of CTP accuracy alter the results only at extremes of parameter settings.
Conclusions: In patients in whom PE is suspected, when CTA is available, even the most sensitive quantitative D-dimer assay is not likely to be cost-effective. When CTA is not available or if its performance is markedly degraded, use of the D-dimer assay has value in combination with CUS and a pulmonary imaging study. These conclusions may not hold for the larger domain of patients presenting to the ED with chest pain or shortness of breath in whom PE is one of many competing diagnoses.     

Prevalence and Significance of Nonthromboembolic Findings on Chest Computed Tomography Angiography Performed to Rule Out Pulmonary Embolism: A Multicenter Study of 1,025 Emergency Department Patients

OBJECTIVES: To evaluate the hypothesis that computed tomography (CT) angiography often yields a result interpreted as an alternative diagnosis to pulmonary embolism (PE) in emergency department (ED) patients. METHODS: This was a multicenter, retrospective, and secondary analysis of consecutive patients in three academic emergency departments. ED patients with symptoms suspicious for PE were included. CT angiography was ordered at the discretion of the treating physician; patients were identified by query of the electronic medical record. Board-certified radiologists gave CT readings, which were reviewed by two independent emergency physicians who categorized the non-PE findings into one of four acuity categories: A = requiring specific and immediate intervention, B = requiring specific action on follow-up, C = requiring no action, and D = indeterminate findings. RESULTS: The prevalence of PE among the 1,025 patients studied was 10% (95% CI = 8% to 12%). In the 921 patients without PE, the mean prevalences (ranges between sites) of concordant categorized non-PE findings were: A = 7% (range 3%-11%), B = 10% (7%-13%), C = 17% (10%-20%), D = 4% (0%-8%), and no ancillary finding = 41% (29% to 45%). The most common category A findings included infiltrate or consolidation suggesting pneumonia (81%), aortic aneurysm or dissection (7%), and mass suggesting undiagnosed malignancy (7%). The overall unweighted agreement was 80% (kappa = 0.72) and weighted agreement was 93% (kappa(w) = 0.84). CONCLUSIONS: In ED patients with suspected PE, the CT angiogram frequently provides evidence suggesting an important alternative diagnosis to PE. Pulmonary infiltrate suggesting pneumonia was the most common non-PE finding.     

Determinants of plasma D-dimer levels in a traveling population

BACKGROUND: Plasma D-dimer measurement is a widely used diagnostic test for assessing individuals with suspected venous thromboembolism (VTE). Whilst a negative test is helpful in ruling out thrombosis, the significance and determinants of an elevated plasma D-dimer level in otherwise healthy subjects are poorly understood. OBJECTIVES: To determine the association between recognized risk factors for VTE and plasma D-dimer levels in an adult population. Subjects and methods: Blood samples for measurement of plasma D-dimer levels were obtained from 1000 adults aged <70 years who were participating in a study investigating the incidence of VTE in long distance air travellers. The relationship between D-dimer levels and selected risks factors for VTE including thrombophilia status was investigated. RESULTS: The median (Inter-quartile range) D-dimer level was 243 ng mL(-1) (175-345). Multivariate analysis showed that plasma D-dimer levels were positively associated with increasing age, larger body mass index, female gender, the use of hormone therapy, thrombophilia state, and the presence of co-morbid conditions. CONCLUSION: Plasma D-dimer levels vary markedly between individuals and are associated with known risk factors for VTE, including the presence of thrombophilia conditions. The potential role for the measurement of plasma D-dimer as a marker for thrombosis risk requires further investigation.     

血浆D-二聚体在肺栓塞患者中的诊断意义

目的:探讨快速定量检测D-二聚体在诊断肺栓塞患者中的临床价值。方法:检测、分析21例经螺旋CT或肺动脉造影确诊的肺栓塞患者及19例健康人(对照组)的血浆D-二聚体含量。结果:与对照组比较,肺栓塞组D-二聚体含量明显升高,有显著性差异(P<0.01)。结论:肺栓塞患者D-二聚体含量明显升高,敏感性为100%,阴性预测值为100%,检测D-二聚体可作为诊断肺栓塞的首选筛选试验。     

Comparison of the Unstructured Clinician Estimate of Pretest Probability for Pulmonary Embolism to the Canadian Score and the Charlotte Rule: A Prospective Observational Study

Objectives: Clinical decision rules have been validated for estimation of pretest probability in patients with suspected pulmonary embolism (PE). However, many clinicians prefer to use clinical gestalt for this purpose. The authors compared the unstructured clinical estimate of pretest probability for PE with two clinical decision rules. Methods: This prospective, observational study was conducted from October 2001 to July 2004 at an urban academic emergency department with an annual census of 105,000. A total of 2,603 patients were enrolled; mean age (± SD) was 45 (± 16) years, and 70% were female. All patients were evaluated for PE using a previously published protocol, including D‐dimer and alveolar dead space measurements, and selected use of pulmonary vascular imaging. All had 45‐day follow‐up. Interobserver agreement for each pretest probability estimation method was measured in a separate group of 154 patients. Results: The overall prevalence of PE was 5.8% (95% confidence interval [CI] = 4.9% to 6.8%). Most were deemed low risk for PE, including 69% by the unstructured estimate < 15%, 73% by the Canadian score < 2, and 88% by the Charlotte rule “safe.” The corresponding prevalence of disease in each of these low‐risk groups was 2.6%, 3.0%, and 4.2%. Weighted Cohen's κ values were 0.60 (95% CI = 0.46 to 0.74) for the unstructured clinical estimate < 15%, 0.47 (95% CI = 0.33 to 0.61) for the Canadian score < 2, and 0.85 (95% CI = 0.69 to 1.0) for the Charlotte rule “safe.” Conclusions: The unstructured clinical estimate of low pretest probability for PE compares favorably with the Canadian score and the Charlotte rule. Interobserver agreement for the unstructured estimate is moderate.     

Use of the d-dimer for Detecting Pulmonary Embolism in the Emergency Department

Background

Assessment for pulmonary embolism (PE) in the emergency department (ED) remains complex, involving clinical decision tools, blood tests, and imaging.

Management studies using a combination of D-dimer test result and clinical probability to rule out venous thromboembolism: a systematic review

BACKGROUND: While the number of patients with suspected venous thromboembolism (VTE) referred to hospital emergency units increases, the proportion in whom the diagnosis can be confirmed is decreasing. A more efficient but safe diagnostic strategy is needed. OBJECTIVE: To evaluate the safety of withholding anticoagulant therapy in patients suspected of VTE based on a diagnostic work-up that combines a clinical decision rule (CDR) with a D-dimer test result without performing additional diagnostic tests. PATIENTS/METHODS: We searched Medline (January 1996-December 2004)-related articles and reference lists of studies in English for prospective clinical studies that managed consecutive patients suspected of VTE and used a D-dimer assay combined with an explicit CDR or implicit clinical judgment. RESULTS: We identified 11 studies in which 6837 consecutive outpatients suspected of VTE were included. In the combined management studies, the overall rate of thromboembolic events was nine out of 2056 patients (0.44 %, 95% CI 0.2%-0.83%) in whom anticoagulants were withheld based on the D-dimer result and a low clinical score. Similar results were obtained with qualitative and quantitative D-dimer tests and with different decision rules. The rate of exclusion varied between 30% and 50% and was highest with a low incidence of VTE among those referred. CONCLUSION: Withholding anticoagulant treatment in patients suspected of VTE on the basis of a work-up consisting of a low clinical probability combined with either a qualitative or quantitative D-dimer test result is safe.     

血浆肌钙蛋白I、脑钠肽联合D-二聚体检查对肺血栓栓塞的临床意义

目的 研究联合应用脑钠肽（BNP）、心肌肌钙蛋白I（cTnI）和D-二聚体（DD）检查在血压正常的肺血栓栓塞（PTE）患者中的临床意义.方法 回顾性分析47例经肺通气/灌注扫描和（或）肺动脉CT成像（CTPA）明确诊断的非大面积肺血栓栓塞病例,以超声心动检查结果将其分为A组（次大面积PTE组）21例和B组（非大面积PTE组）26例,通过其血浆中的cTnI、BNP和DD的水平高低进行分析和评价.结果 血浆D-二聚体水平在A、B组间差异无统计学意义;BNP和cTnI血浆水平在A、B组间差异有统计学意义（P〈0.05）.结论 D-二聚体检查有助于排除诊断,血浆cTnI、BNP水平在次大面积PTE患者中明显升高,联合应用血浆cTnI、BNP和D-二聚体检查在血压正常的PTE患者中有助于筛选出高危患者.     

Role of the Peripheral Intravenous Catheter in False-positive D-dimer Testing

OBJECTIVE: To determine whether inserting a peripheral intravenous catheter (IV) can significantly increase the circulating D-dimer concentration. METHODS: Twenty healthy young adult volunteers underwent cannulation of an antecubital vein with a 20-gauge Teflon IV. Time 0 venous blood was drawn during IV insertion. The IV was salinelocked and left in place for 90 minutes, at which time a second venipuncture was performed in a contralateral antecubital vein (+90 min). A qualitative D-dimer assay [erythrocyte-agglutination assay, SimpliRED (SRDD)] and a quantitative spectrophotometric assay [enzyme-linked immunosorbent assay (EIA), Dimertest Gold] were performed on all samples. Time 0 means (+/-SD) were compared with +90 min means by paired t-test, and SRDD pairs were compared with McNemar's test. RESULTS: Time 0 initial venipuncture blood samples yielded a mean D-dimer concentration of 15 +/- 24 ng/mL, with 2/20 SRDD tests read as positive (95% CI = 1% to 32%). At +90 min, the D-dimer concentration was 33 +/- 21 ng/mL (p = 0.04 vs time 0), with 5/20 SRDD tests read as positive (95% CI = 9% to 49%, p = 0.248). CONCLUSIONS: Insertion of an IV increased the circulating D-dimer concentration (determined by EIA), but did not lead to a significant increase in false-positive conversion of the SRDD. An effort should be made to perform D-dimer testing on "first-stick" blood to optimize specificity. However, a strongly positive D-dimer reaction cannot be ascribed to the presence of an IV.     

Management of suspected pulmonary embolism (PE) by D-dimer and multi-slice computed tomography in outpatients: an outcome study

OBJECTIVES: A prospective outcome study designed to evaluate a simple strategy for the management of outpatients with suspected pulmonary embolism (PE), based on clinical probability, D-dimer, and multi-slice computed tomography (MSCT). METHODS: A cohort of 432 consecutive patients admitted to the emergency department with suspected PE was managed by sequential non-invasive testing. Patients in whom PE was ruled out were not given anticoagulants, but were followed-up for 3 months. RESULTS: Normal D-dimer and low-intermediate clinical probability ruled out PE in 103 patients [24% (95% CI 20-28)]. Seventeen patients had normal D-dimer, but high clinical probability and proceeded to MSCT. All patients proved negative for PE. A total of 329 (76%) patients underwent MSCT examination. Pulmonary embolism was diagnosed in 93 patients [21.5% (95% CI 18-26)] and was ruled out by negative MSCT in 221 patients [51% (95% CI 46-56)]. MSCT scans were determined as inconclusive in 15 (4.5%) patients. No patient developed objectively verified venous thromboembolism (VTE) during the 3-month follow-up period. However, the cause of death was adjudicated as possibly related to PE in two patients, resulting in an overall 3-month VTE risk of 0.6% (95% CI 0-2.2%). The diagnostic algorithm yielded a definite diagnosis in 96.5% of the patients. CONCLUSIONS: This simple and non-invasive strategy combining clinical probability, D-dimer, and MSCT for the management of outpatients with suspected PE appears to be safe and effective.     

Direct Comparison of the Diagnostic Accuracy of Fifty Protein Biological Markers of Pulmonary Embolism for Use in the Emergency Department

Objectives: Pulmonary embolism (PE) is associated with abnormal concentrations of many proteins involved in inflammation, hemostasis, and vascular injury. The authors quantified the diagnostic accuracy of a battery of protein biological markers for the detection of PE in emergency department (ED) patients. Methods: A random and a consecutive sample of ED patients evaluated for PE were prospectively enrolled at two academic EDs between August 2005 and April 2006. A plasma sample was obtained at enrollment, and all patients were followed by telephone and medical record review at 90 days for the development of venous thromboembolism (VTE) defined as PE or deep venous thrombosis (DVT), requiring the consensus of two of three blinded physician reviewers. Measurements of potential biological markers were performed by technicians blinded to the study objectives. The diagnostic accuracy of each biological marker was determined by the area under the receiver operating characteristic (ROC) curve. Results: Fifty potential biological markers were measured in 304 ED patients, including 22 patients (7%, 95% confidence interval [CI] = 4% to 10%) with VTE. Fourteen biological markers demonstrated an area under the curve (AUC) with the lower limit of the 95% CI ≥ 0.5. Of these, three demonstrated an AUC ≥ 0.7: D‐dimer (0.90), C‐reactive protein (CRP; 0.78), and myeloperoxidase (MPO; 0.78). Conclusions: From 50 candidate biological markers, only D‐dimer, CRP, and MPO demonstrated sufficient diagnostic accuracy to suggest potential utility as biological marker of PE.     

Impact of a Negative Evaluation for Underlying Coronary Artery Disease on One-year Resource Utilization for Patients Admitted with Potential Acute Coronary Syndromes

Reduction in emergency department (ED) overcrowding is a major Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) initiative. One major source of ED overcrowding is patients waiting for telemetry beds. OBJECTIVE: To determine whether, in patients admitted with a potential acute coronary syndrome, a negative evaluation for underlying coronary artery disease would reduce ED and hospital revisits over the subsequent year compared with patients who did not receive an evaluation for underlying coronary artery disease. METHODS: Nine hundred ninety-nine consecutive patients admitted for potential acute coronary syndromes through the ED during a one-year period were screened for inclusion. Patients who had a negative evaluation for underlying coronary disease were compared with patients who were not evaluated for underlying coronary artery disease for subsequent ED visits, hospital admissions, and cardiac resource utilization over the year following the index visit via a health system-wide computerized record review. Patients with positive tests or biomarkers at the index visit were excluded. Each repeat visit was rated as "potentially cardiac" or "noncardiac." Results of echocardiograms, stress tests, and catheterizations and information about in-hospital deaths were obtained. RESULTS: Six hundred ninety-two patients met the inclusion criteria: 556 patients received no evaluation for underlying coronary artery disease, 116 had a negative stress test, and 20 had a negative cardiac catheterization during the index visit. Patients with no evaluation for underlying coronary artery disease and patients with a negative evaluation had similar likelihoods of a repeat ED visit (negative test 39.0% vs. no test 40.3%; p = 0.85) and repeat hospital admission (28.7% vs. 31.5%; p = 0.61). The rates of a potentially cardiac-related ED visit (21.3 vs. 23.4%; p = 0.65) and hospital admission (17.7% vs. 20.7%; p = 0.48) were not significantly different. The two populations had similar utilization rates of echocardiograms, stress tests, and catheterizations (p > 0.70 for all). CONCLUSIONS: For patients admitted to the authors' institution with a potential acute coronary syndrome, there was no association between a negative evaluation for underlying coronary artery disease and overall or potentially cardiac ED visits, admissions, or cardiac resource test utilization over the year following the index visit.